Communication performance of the wireless tag is improved by providing an SRAM provided with an RF battery in the wireless tag provided with a CPU to speed up the CPU system. Moreover, rewriting of data in a memory of a wireless tag provided with a CPU is enabled. An RF battery includes an antenna circuit, a power supply portion, and a power storage device. A function as a non-volatile memory is provided to an SRAM by combining the SRAM and an RF battery.